What we have here is a case of large numbers vs other large numbers, preventing a clear-cut case for high or low probability.
A simple version of the Drake equation applies here. The probability that we will be contacted by aliens is:
A. the probability of intelligent life evolving on at least one other planet, multiplied by
B. the probability that a given intelligent species will develop interstellar exploration, or intergalactic exploration as the case may be, before it becomes extinct, multiplied by
C. the probability that a given species with interstellar/galactic exploration will actually find us before we become extinct ourselves.
(I say "exploration" rather than "travel", because the aliens might not have to be in our vicinity to find and contact us.)
If you remove the "other" from A to make, "the probability of intelligent life evolving on at least one planet," its probability becomes 1 (certain), as our existence proves it has already happened. If it happened here, nothing prevents it happening elsewhere, so A is indeed very close to 1 and very likely indeed. In other words, they're probably out there.
B is where the trouble starts. Interstellar or intergalactic travel or communication within reasonable timeframes (say, between any two stars in a galaxy within a lifetime) might actually be impossible, if the universe's inherent speed limit of 300,000km a second cannot be circumvented. B could be zero, and therefore alien contact might simply be impossible.
If instead there is a way to cross the cosmos which we haven't discovered yet, we won't know how long that takes until it happens. The danger is that it requires a species to spend a very long time working from a baseline of technologies with which it might inadvertently destroy itself. We're at that stage right now; our theories of deep space travel stem from some of the same research and the same minds as our atomic weaponry. The terrible risk of this particular period in a civilisation's existence appears to lower B considerably.
Finally, C is a function of A and the possibly infinite size of the universe. If every intelligent species which will ever arise has an volume of space to itself so big it will take the rest of its lifespan to explore (likely so far, since we've found nothing in the places we can see properly), no two may ever cross paths. Since the universe is expanding, the chances of contact are shrinking all the time, especially if the species are in separate galaxies, clusters or superclusters.
Tragically, the most likely case appears to be that there's intelligent life all over the universe, forcibly segregated by the tyranny of time and distance. Of course, ET could show up tomorrow and waggle a glowing finger at our flawed view of the universe.
Perry Marshall presents himself as an invincible defender of his supposed proof of an Intelligent Designer, standing atop a mountain of vanquished counter-arguments from hordes of atheists.
The plain logical error in the argument is in the second premise, and it's the one logical fallacy I come across more than any other: an argument from ignorance. "There is no natural process known to science that creates coded information." That's not the same as saying there really is no such natural process (which would be a simple unsupported statement rather than a fallacy), but it expects us to assume as much. Is Mr Marshall, or any human alive, familiar with "all codes" in the universe? What qualifies anyone to make such a sweeping statement? This attempted proof by elimination of the origin of DNA must leave room for unknown alternatives to maintain any honesty, and is therefore not a real proof.
I realise that the fact of the logical error is not such a brilliant counter-argument when you're actually trying to convince people. There are plenty more objections, and Marshall has posted and replied to many on his site. He hasn't always done so convincingly, though you can judge that for yourself. I'll just take one approach as an exercise.
As support for the argument that all codes are designed by a mind, Marshall argues that random processes do not produce information. (I've been through this at length.) His primary demonstration is his own text-based random mutation generator which takes a sentence and, through single-letter changes, turns it to nonsense.
Marshall admits that the mutation utility does not simulate natural selection, the non-random element of evolution. Furthermore, he's not interested in adding that functionality to test his own argument. (He says instead that the reader is free to do it for him; if someone has taken him up on this, please let us know. Meanwhile, here's a more complex simulator.)
He argues that natural selection would only create sensible sentences if words only mutated into other meaningful words, but that's not applying natural selection at the letter level. An ideal extension of his program would present several choices of mutation at each step, and allow those letter mutations which destroy the legibility of a word to be manually or automatically ruled out. (The real world equivalent is a serious birth defect, which would keep a creature from breeding or even living long enough to breed.) In Marshall's program, detrimental mutations are allowed to compound until all sense is lost. Of course we won't likely get anything useful out of it.
Forgetting even the mechanism of natural selection, I submit a basic argument for the possibility of chance creating information which I've used before: think of a large grid of squares which can be either black or white, but all start as white. If you randomly pick the colour of every square at once, there is a chance, however small, that the newly black squares will form a simple but clear picture of a rectangle, or the letter G, or Elvis. Without adding any extra material, chance can increase the amount of information the grid provides. The prebiotic chemicals only had to manage a feat like this once, given potentially unlimited opportunities, to come up with DNA or its precursors.
I think what you're saying is that because God created life billions of years ago, and we can't, God is better than us at molecular biology.
If we last another 6 billion years we probably will succeed in creating new life. We've made tremendous progress in just the 50-ish years since the Miller-Urey experiments, which created 22 kinds of amino acids from primitive swamp gas and lightning. We haven't succeeded in causing life to emerge yet, but we can produce all kinds of precursors. If we have 120 million times as long to try, I think we'll get there.
As for the initial life that evolved into us, it needn't have been created at all. The very fact that we're finding it so difficult to do deliberately suggests that it happens more easily as a natural process. The Earth is vast, the chemical ingredients it provides are diverse and plentiful and they had billions of years to mix. The sheer number of possible combinations is staggeringly large. The odds against one of those combinations resulting in life? Not so large.
If you're going to argue that abiogenesis is not science, it might help to define science first.
Science is the formulation of natural explanations for observable phenomena in the universe. Abiogenesis (the emergence of life from non-life), while not yet observed itself, is a natural explanation for the observable phenomenon of life. It is therefore a scientific hypothesis, and yes, it is science. What it is not (yet) is a theory.
Though some natural selection may have occurred in the process, abiogenesis should not be classified as chemical evolution. It may have been a rapid, non-cyclical process instead. We freely admit that we have no clue how it happened.
At least until we do observe a second abiogenesis in a lab or in nature (positing that the event which produced us was the first), not only do we stick to speculation as to how it happened, but we refrain from stating 100% certainty that it did happen. If evidence of intelligent design were to emerge (say, actual physical impressions of fingerprints in our DNA) we would soon abandon the hypothesis that we are the products of abiogenesis. We would then try to determine whether the designer was a god, an alien or an extinct Earth creature, and in all three cases start to hypothesise about the abiogenesis and evolution of that being, if any.
This is the difference between a scientific hypothesis and a faith position. We assume a scientific hypothesis for practical purposes as the best current explanation until a better one comes along, at which point we chop and change. We're not precious about it at all, at least until it accumulates enough evidence to be declared a theory. A man with a faith position defends it to the end, because he usually expects no contradictory (or even supporting) evidence to present itself.
Another difference is that a hypothesis must be falsifiable, which means there must be some hypothetical event which demonstrates it is false. Our abiogenesis is falsifiable because we might find firm evidence of a creator, like a signature or a work log billions of years old. By comparison, what would falsify the intelligent creation of life? Nothing. Even if we achieved abiogenesis in a lab, it might be the case that although abiogenesis is possible, we were still designed.
On the basis of this last point, I submit to you the idea that intelligent creation of life is a faith position where abiogenesis is not. There may be additional ways to establish this comparison, but I'll leave it at that for now.
I've seen the genetic code argument before, you know. The idea is that all codes are intelligently designed, so the existence of one in DNA proves a designer. That's an argument from ignorance because there is no evidence that a code is impossible without a designer. Further, if you present this argument, I can provide examples of naturally occurring codes which have nothing to do with life, like the means by which mineral crystals can transmit their structure to non-crystallised material.
There's another side to the genetic code argument which states that it's impossible for new information to appear naturally. We've been over that here.
Let's go through this very carefully.
- We have about 8,000 years of recorded human history. Humans are the only creatures who have ever deliberately recorded it. All time before that is referred to as PREhistory for a reason; the universe pre-dates recorded history. By about 15 billion years.
- The Big Bang was a sudden expansion of matter. It did not create any heat, because all heat was contained within it; it merely dispersed heat like it did matter. It did not necessarily create anything, since nothing stops the matter from having existed before the Bang. It did not destroy anything either, because there was probably nothing outside the Bang that it could destroy. Comparing the Big Bang to an explosive detonation is a gross oversimplification.
- Present-day black holes do contain vast amounts of matter compressed to a single point, or singularity. It happens when the gravity of an object is great enough to overcome the magnetic fields keeping the atoms apart. Current physics do allow for this.
- Even if time as we know it resulted from the Big Bang, it's not necessarily all the time there's ever been. What if another system of time and space existed, and the Big Bang spawned from this? Perhaps another universe?
An atheist doesn't know how the heck the Big Bang happened, because we haven't found enough evidence to make any theory remotely certain. I'm comfortable with that. If I adopted one hypothesis as the truth now, I'd have to fault every other theory out there without any support at all.
Finally, don't take offence but to assert beyond doubt that a God is responsible for something merely because of the absence of known alternatives is the very model of an argument from ignorance.
I won't cover abiogenesis (the origin of life) here, because neither has MrPeters.